The growing incidence of obesity and type 2 diabetes became the major global health problem. The peculiarities of energy metabolism in the development of both these conditions are of particular interest. This book, therefore, provides an overview of the following aspects: body composition assessment using laboratory techniques and bedside methods, estimation of resting energy expenditure, methods for the evaluation of energy intake, assessment of psychological factors influence on eating behavior. All these aspects are covered in the context of obesity, type 2 diabetes and metabolic syndrome thus, will help to understand the importance of changes in resting metabolic rate possibly preceding the development of type 2 diabetes; explain the advantages and limitations of bedside body composition assessment methods and suggest their utilisation in clinical practice; reveal new aspect of regional body fat distribution, influencing the precision of different body composition measuring techniques; show novel relations of psychological factors influence on eating behaviour in type 2 diabetes and analyse the compliance to the dietary advice and treatment for weight loss.